Merge pull request #7549 from poettering/ptyfwd-fixes

pty forwarder fixes

src/run/run.c

@@ -1085,6 +1085,9 @@ static int start_transient_service(
                                 return log_error_errno(r, "Failed to create PTY forwarder: %m");
 
                         pty_forward_set_handler(c.forward, pty_forward_handler, &c);
+
+                        /* Make sure to process any TTY events before we process bus events */
+                        (void) pty_forward_set_priority(c.forward, SD_EVENT_PRIORITY_IMPORTANT);
                 }
 
                 path = unit_dbus_path_from_name(service);
@@ -1100,7 +1103,7 @@ static int start_transient_service(
                 if (r < 0)
                         return log_error_errno(r, "Failed to add properties changed signal.");
 
-                r = sd_bus_attach_event(bus, c.event, 0);
+                r = sd_bus_attach_event(bus, c.event, SD_EVENT_PRIORITY_NORMAL);
                 if (r < 0)
                         return log_error_errno(r, "Failed to attach bus to event loop.");
 

src/shared/ptyfwd.c

@@ -171,6 +171,30 @@ static bool ignore_vhangup(PTYForward *f) {
         return false;
 }
 
+static bool drained(PTYForward *f) {
+        int q = 0;
+
+        assert(f);
+
+        if (f->out_buffer_full > 0)
+                return false;
+
+        if (f->master_readable)
+                return false;
+
+        if (ioctl(f->master, TIOCINQ, &q) < 0)
+                log_debug_errno(errno, "TIOCINQ failed on master: %m");
+        else if (q > 0)
+                return false;
+
+        if (ioctl(f->master, TIOCOUTQ, &q) < 0)
+                log_debug_errno(errno, "TIOCOUTQ failed on master: %m");
+        else if (q > 0)
+                return false;
+
+        return true;
+}
+
 static int shovel(PTYForward *f) {
         ssize_t k;
 
@@ -306,7 +330,7 @@ static int shovel(PTYForward *f) {
 
         /* If we were asked to drain, and there's nothing more to handle from the master, then call the callback
          * too. */
-        if (f->drain && f->out_buffer_full == 0 && !f->master_readable)
+        if (f->drain && drained(f))
                 return pty_forward_done(f, 0);
 
         return 0;
@@ -547,6 +571,28 @@ bool pty_forward_drain(PTYForward *f) {
          */
 
         f->drain = true;
-
-        return f->out_buffer_full == 0 && !f->master_readable;
+        return drained(f);
+}
+
+int pty_forward_set_priority(PTYForward *f, int64_t priority) {
+        int r;
+        assert(f);
+
+        r = sd_event_source_set_priority(f->stdin_event_source, priority);
+        if (r < 0)
+                return r;
+
+        r = sd_event_source_set_priority(f->stdout_event_source, priority);
+        if (r < 0)
+                return r;
+
+        r = sd_event_source_set_priority(f->master_event_source, priority);
+        if (r < 0)
+                return r;
+
+        r = sd_event_source_set_priority(f->sigwinch_event_source, priority);
+        if (r < 0)
+                return r;
+
+        return 0;
 }

src/shared/ptyfwd.h

@@ -54,4 +54,6 @@ void pty_forward_set_handler(PTYForward *f, PTYForwardHandler handler, void *use
 
 bool pty_forward_drain(PTYForward *f);
 
+int pty_forward_set_priority(PTYForward *f, int64_t priority);
+
 DEFINE_TRIVIAL_CLEANUP_FUNC(PTYForward*, pty_forward_free);